This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This is a non-randomized natural history non-treatment study in which a total of 800 subjects including 200 normal controls, 400 individuals with MCI, and 200 subjects with mild AD will be recruited at approximately 50 sites in the United States and Canada. The major goals of the ADNI are to: 1. Develop improved methods which will lead to uniform standards for acquiring longitudinal, multi-site MRI and PET data on patients with Alzheimer s disease (AD), mild cognitive impairment (MCI), and elderly controls. 2. Acquire a generally accessible data repository which describes longitudinal changes in brain structure and metabolism. In parallel, acquire clinical cognitive and biomarker data for validation of imaging surrogates. 3. Develop methods which will provide maximum power to determine treatment effects in trials involving these patients. 4. Test a series of hypotheses based on the clinical and biomarker data as outlined in the statistical analysis section.